Process for making long chain unbranched alkyl tertiary amines



PROCESS FOR MAKING LONG CHAIN UNBRANCHED ALKYL TERTIARY AMINES FiledJune 28, 1965 Straight-Chain Paraifins 10 To 20 Carbons Distill ChlorineUnreacted Paraffins Reaction Zone No. l Chlorination Bottoms Di- AndPoly- Chloro I araffins Alkyl chlorides action Zone No. 2

ination Fater And Alcohol Amine Hydrochloride Solution Unreacted MatterAlkali io Unreacted i solut a Paraffins V F And Alkyl ch1ride5 LnineKydrochloride Solution Brine Free Amine Clarified Amino Filter CakeUnited States Patent ()3 3,385,893 Patented May 28, 1968 ice ABSTRACT OFTHE DISCLGSURE This relates to the preparation of long chain unbranchedaliphatic tertiary amines by subjecting straightchain paraffins, in thepreferred range of 10 to carbon atoms, to chlorination. The resultantalkyl chlorides are then converted into suitable tertiary amines byreacting, under pressure, with an excess of an alkyl secondary amine,such as dimethyl amine, at about 100 to about 250 C. over a period ofabout 4 to 20 hours. The alkyl tertiary amine hydrochloride formed inthe reaction is then separated from the reaction mixture and is treatedwith an alkaline solution to yield the free tertiary amine.

The object of the present invention is the preparation of long chainunbranched aliphatic tertiary amines of low cost.

This application is a continuation-in-part of Ser. No. 384,489, filedJuly 22, 1964, now abandoned.

Tertiary amines which possess useful and valuable properties are wellknown to the art. They are, however, rather costly, being usuallyprepared from naturally occurring fatty alcohols such as are present inspermaceti and the like, or otherwise from fatty acids or their estersby reduction, as by hydrogenation. Methods well known to the art forpreparing the amines consist, in general, of such processes asconverting the fatty alcohols to their halides, followed by reaction ofthese halides with secondary amines to form tertiary amines as theirhydrohalides from which they can be recovered by treatment with alkalisolution; or by such stepwise processes as the saponification ofnaturally occurring fats with ammonia; the dehydration of the ammoniumsoaps to the amides; the further dehydration of the amides to thecorresponding nitriles; followed by hydrogenation to produce mixtures ofmainly primary and secondary plus some tertiary long chain amines whichmay be separated by fractional distillation into suitable fractions, oneof which is the preferred primary amine; this in turn is followed byalkylation, as by means of formaldehyde and formic acid by a modifiedMannich reaction; or by reaction with an alkyl halide such as methylchloride to yield tertiary amine hydrohalides from which the free aminescan be obtained by adding a solution of caustic alkali. By this meansare obtained tertiary amines containing one long hydrocarbon radicalplus two short radicals such as methyl, along with more or less tertiaryamine containing two long chain and one short chain radicals.

These tertiary amines which may be either mixtures containing a wideseries of homologous amines, or as the result of distillation a narrowerrange of such homologs, or where desired a segregated amine of adefinite chain length, may then be further processed by reacting themunder suitable conditions as, for example, with an oxidizing agent suchas hydrogen peroxide, an organic peroxide, or ozone and the like, toproduce amine oxides. Such oxidation processes are well known to the artand are in use for the manufacture of certain surface active agents ofcommercial value. The tertiary amines may also be processed by treatingthem with alkylating agents such as methyl chloride, ethyl bromide,henzyl chloride, dimethyl sulfate and the like, in which casequz-itcrnary ammonium salts are formed. These compounds are valuablearticles of commerce with a wide range of applications, including suchuses as sanitization and disinfection, fabric softening and theprevention of the accumulation of static electric charges. The tertiaryamines may also be used to prepare amphoteric surface active agents ofthe betaine type as, for example, by reaction with chloro acetic acid orits salts and the like. Other uses for these fatty tertiary amines willbe readily apparent to those skilled in the art.

These operations, because of their complexity, are necessarily costly.Since the raw materials either naturally occurring or synthesized arealso relatively expensive, the end products often have been of limitedcommercial applicability, solely for economic reasons.

This invention proposes to reduce these costs substantially by employingmaterials of low cost; namely, straight chain parafiins obtained eitherfrom suitable grades of petroleum oil or synthetically derived from thecondensation of ethylene by methods now in commercial use. The preferredrange of chan lengths for the synthesis of tertiary amines of widecommercial applicability is from 10 to 20 carbon atoms.

Straight chain paraffins are to be preferred over their branched chainisomers for various reasons, principal of which are: (l)polychlorination is more likely on the branched chain; (2) chlorinationis most likely on the tertiary carbons, and such halides are lessreactive; and (3) the surface active properties of branched chaincomounds are inferior for a given molecular weight to those of thestraight chain analogs.

Where naturally occurring, i.e., petroleum based, paratfins are to beused, they can be separated from their branched chain isomers by methodswell known to the art and of present commercial application; among theseprocesses are those involving the use of molecular sieves and those inwhich urea adducts are prepared and separated and resolved.

Stnaight chain paraffins of the preferred range of 10 to 20 carbons aresubjected to chlorination at temperatures ranging from 0 to C., butpreferably 30 to 70 C. Actinic light, iodine or other suitable catalystmay be employed, if desired. Reaction is continued until from 5 to ofthe theoretically calculated amount of chlorine has reacted, butpreferably about 10 to 30% of the theoretical amount in order to preventor to minimize polychlorination. We may chlorinate to the higher degreeshould we desire to obtain di-chloroparafiins as well; such can berecovered or separated by fractional distillation as by-products ofvalue. However, such distillation is not a necessary part of the processat this stage.

The alkyl chlorides so obtained are then converted into sutiabletertiary amines as, for example, the alkyl dimethyl amines, by reactingthem under pressure with an excess of dimethyl amine at temperatureranging from 100 to 250 C., but preferably at to C. over a period offrom 4 to 20 hours until no further reaction occurs; this point may bedetermined by argentometric titration. Preferably a quantity of a polarsolvent is included in the reaction mixture to increase the reactionrate.

On completion of reaction, the unreacted excess of dimethyl amine orother amine used in the process is recovered for reuse by distillationand Water is added to dissolve the tertiary amine hydrochloride formed,with or without the addition of alcohol or the like to facilitate clearseparation.

The amine hydrochloride solution is removed and upon addition of therequired amount of alkali to liberate the free amine from its salt, theproduct separates as an oily layer. This may be clarified as byfiltration to remove gross dirt, and it may be dried as by heating todrive off the small amount of dissolved or dispersed water, or it may beused in its crude form. For the sake of good color, it is desirable torid it of such foreign matter.

The unreacted parafin and chloroparaffin on drying may be used forrecycling.

The recovered tertiary amine may then be converted into the tertiaryamine oxide, if desired, by reacting it with aqueous hydrogen peroxide,for example, with or without the addition of a solvent such as ethylalcohol or isopropanol, by heating the mixture with agitation attemperatures ranging from the ambient to about 100 C., the reaction rateand the color of the product being optimum at about 40 to 80 C. Uponcompletion of the reaction, the product exists as a single phase and adilute solution thereof in water is clear.

Other reactions of the tertiary amines and some of their products areillustrated in the following examples.

The drawing, FIGURE 1, illustrates a flow chart embodying the novelfeatures of my process. This chart 1- lustrates graphically theessential sequence of steps of my process in producing straight chainalkyl chlorides, starting with straight chain parafiins, preferablyhaving to carbon atoms. The flow chart also indicates how the unreactedparatfins may be recovered and recycled for reuse. Also, the dichloroandother polychloroparaflins may be separated from the alkyl chlorideswhich are to be treated further. The chart also indicates that theexcess or unreacted amines which are used to react with the alkylchlorides are distilled from the react on zone and reused. Thereafter,the chart indicates that the unreacted parafhns and chloroparafiins maybe separated from the solution of tertiary amine hydrochloride in whichthey are not soluble and returned for recycling, following which thetertiary amines are liberated from their combination with HCl bytreatment with caustic alkali. The tertiary amines may then "beclarified and dried. The process can be carried out continuously bymeans of suitable apparatus so as to yield maximum yields with efficicntutilization of all materials used in the process by recycling andrecovering unreacted agents which are reused, thereby reducing costs.

The amines so produced may then be reacted with hydrogen peroxide toform amine oxides, or they may be treated with other reactants insteadto form other surface active compounds.

Example I 299 grams or 1.5 mols of a straight chain paraflin cut ofwhich 95% was N-tetradecane was chlorinated in an agitated glass flaskunder diffused daylight, the chlorine gas being introduced by means of'a fritted glass sparger at to C. with cooling as required to moderatethe exothermic reaction. When the weight increase amounted to grams orof the theoretical amount of chlorine for monochlorination, the productwas heated in vacuo to remove dissolved chlorine and hydrogen chloride.

The material was then distilled, to remove a forerun of unreactedhydrocarbon, and then to obtain a main cut amounting to 51% of the stillcharge. Vapor phase chromatographic analysis indicated amonochlorotetradecane content of 70%, or 36% of available monochlorideon the total charge.

Example II A commercially available mixture of N-aliphatic hydrocarbonsof C to C chain length, obtained from Shell Chemical Company, waschlorinated in a similar manner to that of Example I. 265 grams of thehydrocarbon was reacted with 50 grams of chlorine at 50 C. during threehours.

The crude product was distilled to yield a forerun of 145 grams ofunreacted material, a main cut of 106 grams, and a still bottoms of 30grams.

The main fraction assayed 18.7% of combined chlorine; the theoreticalcontent for a C chain length is 16.25%.

Example III 396 grams or 2.0 mols of the tetradecane of Example I wasagitated in a glass flask under diffused daylight and chlorine wasbubbled in via a fritted glass diffuser; the charge was cooled tomoderate the exothermic reaction which was conducted at about 35 C.

Reaction was continued until 21 grams weight increase had occurred,equivalent to absorption of 30% of the theoretical amount of chlorinefor monochlorination.

The reaction mass was heated in vacuo to remove the dissolved gases andthen to distill off the unreacted hydrocarbon. The residue in the flaskamounted to grams which assayed 15.6% combined chlorine.

Example IV In a similar manner, N-decane, N-dodecane, N-hexadecane andN-octadecane and mixtures of straight chain paraflins of chain lengthsof the range of C to C were chlorinated.

Example V 100 grams of the topped chlorotetradecane of Example III wasreacted with dimethyl amine in a stainless steel pressure vessel at toC. for a period of seven hours. The dimethyl amine was in the form of a25% solution in isopropanol and in 300 mol percent proportion to thealkyl chloride.

The excess dimethyl amine was distilled off along with the isopropanol.The residue was taken up in water and extracted with petroleum ether toremove inert material such as hydrocarbons and residual alkyl chloride.The aqueous layer containing the tetradecyl dimethyl amine hydrochloridewas then treated with caustic soda solution to liberate the amine as anoily layer which was washed and dried. The yield was 90 grams.

Example VI 33.5 grams of the tetradecyl dimethyl amine of Example V wasdissolved in 80 grams of isopropanol and 35 grams of water in a flaskequipped with a mechanical stirrer, a reflux condenser, and a droppingfunnel charged with 10 grams of 50% hydrogen peroxide. The solution waswarmed to 40 C. and the hydrogen peroxide was added while maintainingthe temperature between 40 and 80 C., cooling and heating as required.The reaction was continued for several hours until the mixture washomogeneous and gave a clear solution in water. The resulting tetradecyldimethyl amine oxide was adjusted to 15% strength.

Example VII The topped chlorides of Examples III and IV were reactedwith dimethyl amine as in Example V and stripped of excess dimethylamine and alcohol. The alkyl dimethyl amine was liberated from thehydrochloride by means of treatment with sodium hydroxide solution andthe crude aminewas vacuum dried without extraction with solvent. Afterfiltration to remove gross dirt, a portion of the crude amine wasconverted into the corresponding amine oxide by the procedure of ExampleVI. Other portions were reacted with alkylating agents as described insucceeding examples.

Example VIII The main fraction of C to C monochloride of Example II wasreacted with dimethyl amine solution under less drastic conditions thanthose prescribed in Example V. 47.5 grams of the alkyl chloride and 150grams of a 22% solution of dimethyl amine in isopropanol were heated at100 C. for nine hours and then cooled.

Titration of an aliquot of the resulting solution with silver nitrateindicated 1.24% of ionic chlorine, whereas at full reaction, 4.43%should theoretically be present; under these conditions, 28% of thehalide had reacted to form the corresponding C to C dimethyl amine.

The solution was stripped of dimethyl amine and alcohol, the residue wastaken up in water and extracted with petroleum ether to remove unreactedor inert matter, and the aqueous layer was made alkaline with causticsoda in order to separate out the oily amine as in Example V.

Example IX 123 grams or 0.51 mol of tetradecyl dimethyl amine preparedby the method of Example V and 63 grams or 0.50 mol of benzyl chloridewere heated under reflux in an agitated flask along with 180 grams ofwater at 80 to 100 C., until the mixture became homogeneous and then forone-half hour longer. At the end of this period, argentometric titrationindicated that the reaction was substantially complete. The product wasa yellow viscous solution of tetradecyl dimethyl benzyl ammoniumchloride.

Example X The washed and dried C to C dimethyl amines of Example VIIIwere reacted with benzyl chloride in the same manner and in the samemolar proportion as in Example 1X.

The product was tested bacteriologically by the Official PhenolCoeflicient Method of the U.S. Department of Agriculture against S.typhosa and S. aureus. The respective phenol coeflicients on the 100%basis were 287 and 250.

Example XI Dodecyl dimethyl amine, one of the products of Example VII,was reacted in stoichiometric proportion with chloro acetic acid. Threeparts by weight of the latter and one part of propylene glycol wereagitated in a threeneck flask while the dodecyl dimethyl amine wasadded. The temperature rose sharply to about 55 C. The mixture washeated further to about 80 C., when the reaction became stronglyexothermic, and it was necessary to apply cooling to maintain atemperature of 100-410 C. This temperature was maintained for threehours, at the end of which time argentometric titration indicated about95% completion.

The product, the hydrochloride of dodecyl dimethyl betaine, was thenneutralized in a second agitated flask containing two equivalents ofcaustic soda in aqueous solution, to which it was slowly added whileagitating and cooling. The final product had a pH of 6.0, and is thesodium salt. It is an efiective foaming and wetting agent and isamphoteric in character, containing both a carboxyl and an amino group.

Although in the above examples, dimethyl amine was employed as areactant with the parafiinic chlorides, other secondary amines may beemployed as well, for example, diethyl amine, morpholine and the like,and under more vigorous conditions, diethanolamine and methylethanolamine and the like.

I claim:

1. The process of making long chain unbranched alkyl tertiary amineswhich comprises the steps of treating a straight chain paratfincontaining from 10 to 20 carbon atoms with chlorine at a temperature of0 to C., treating the resulting alkyl chloride with an alkyl secondaryamine at a temperature of 100 to 250 C., separating the alkyl tertiaryamine hydrochloride formed thereby from the reaction mixture andtreating said tertiary amine hydrochloride with an alkaline solution toyield the free alkyl tertiary amine.

2. The process of claim 1 wherein the straight chain paraflin issubjected to chlorination at a temperature from about 30 to about 70 C.

3. The process of claim 1 wherein the chlorinated paraflin is treated toseparate the monochloroparaflin therefrom.

4-. The process of claim 1 wherein the alkyl monochloride is reactedwith an excess of alkyl secondary amine at a temperature from to C. fora period of about 4 to 20 hours in the presence of a polar solvent untilno further reaction occurs.

5. The process of claim 4 wherein the unreacted excess of alkylsecondary amine is recovered by distillation and reused for reactingwith additional straight chain chloroparaflin.

6. The process of claim 1 wherein the alkyl monochloride is treated withan excess of alkyl secondary amine in the presence of a polar solvent.

7. The process of claim 1 wherein the straight chain parafiin reactedwith chlorine comprises a mixture of naliphatic hydrocarbons of C to Cchain length to produce corresponding monochloro hydrocarbons and thesaid monochloro hydrocarbons are reacted with dimethyl amine in thepresence of isopropanol.

8. The process of claim 1 wherein the alkyl secondary amine is a memberof the group consisting of dimethyl amine, diethyl amine,diethanolamine, methyl ethanolamine and morpholine.

9. The process of claim 1 wherein the straight-chain paraflin is amember of the group consisting of u-tetradecane, n-decane, n-dodecane,n-hexadecane, n-octadecane, and a mixture of n-aliphatic hydrocarbons ofC to C chain length.

' References Cited UNITED STATES PATENTS 3,267,147 8/1966 Sheeran 2605833,272,881 9/1966 Kapur et al. 260668 3,287,411 11/1966 Wakeman 260-5853,299,142 1/ 1967 Simpson 260585 NICHOLAS S. RIZZO, Primary Examiner.

ALEX MAZEL, JOSE TOVAR, Examiners.

